Method for wet flue gas desulfurization

Abstract

A wet flue gas desulfurization process uses byproduct polyester streams such as those from the production of PLA and/or PGA consisting of hydroxy acids and other organic acids to catalyse the solubilization of calcium from limestone and to further catalyse the reaction of calcium with SO 2 for desulfurization and thereby provide significant improvement in process efficiency.

We claim: 
     
       1. A process for wet flue gas desulfurization comprising the steps of:
 preparing a slurry of alkaline solids selected from the group consisting of sodium carbonate, potassium carbonate, calcium carbonate and magnesium carbonate; 
 activating the slurry of alkaline solids by mixing enantiopure, L or D, monomers and polymers of lactic acid, with or without monomers and polymers of glycolic acid or other hydroxy acids into the slurry to promote solubilization of the alkaline solids; 
 bringing untreated flue gasses into intimate contact with the slurry mixture, where the monomers and polymers of hydroxy acids catalyze a reaction of flue gas sulfurs and solubilized alkalines to remove sulfur from the flue gas; and 
 releasing the desulfurized flue gas into the atmosphere. 
 
     
     
       2. The process of  claim 1 , wherein the selected alkaline solids are calcium carbonate in the form of limestone. 
     
     
       3. The process of  claim 1 , wherein the enantiopure monomers and polymers of lactic acid are in the form of a byproduct polyester stream from the manufacture of polylactic acid (PLA). 
     
     
       4. The process of  claim 1 , wherein the monomers and polymers of hydroxy acids are in the form of a byproduct polyester stream from the manufacture of polyglycolic acid (PGA). 
     
     
       5. The process of  claim 1 , wherein poly hydroxy acids, such as gluconic acid and its homologues are also added to the slurry mixture. 
     
     
       6. The process of  claim 1 , wherein preparing the slurry includes the step of reducing particle size of the alkaline solids. 
     
     
       7. The process of  claim 6 , wherein the acid monomers and polymers are introduced while preparing the slurry. 
     
     
       8. The process of  claim 6 , wherein the step of reducing particle size of the alkaline solids is accomplished by milling and the acid monomers and polymers are introduced to reduce frictional losses. 
     
     
       9. A process for a wet flue gas desulfurization wherein the inherently enantiopure monomers and polymers of hydroxy acids in a byproduct polyester stream from the manufacture of PLA act as an agent for catalyzing the reaction of flue gas sulfurs and alkalines for removal of sulfur from the flue gas. 
     
     
       10. A process for a wet flue gas desulfurization wherein a byproduct polyester stream from the manufacture of PGA acts as an agent for catalyzing the reaction of flue gas sulfurs and alkalines for removal of sulfur from the flue gas. 
     
     
       11. A process for wet flue gas desulfurization comprising the steps of:
 preparing a slurry of alkaline solids selected from the group consisting of sodium carbonate, potassium carbonate, calcium carbonate and magnesium carbonate; 
 activating the slurry of alkaline solids by mixing a byproduct stream taken from the manufacture of polyesters, the stream comprising enantiopure monomers and polymers of hydroxy acids, into the slurry to promote solubilization of the alkaline solids; 
 bringing untreated flue gasses into intimate contact with the slurry mixture, where the monomers and polymers of hydroxy acids catalyze a reaction of the flue gas sulfurs and activated alkaline solids to remove sulfur from the flue gas; and 
 releasing the desulfurized flue gas into the atmosphere. 
 
     
     
       12. The process of  claim 11 , wherein the polyester byproduct stream is derived from the manufacture of polylactic acid (PLA). 
     
     
       13. The process of  claim 11 , wherein the polyester byproduct stream is derived from the manufacture of polyglycolic acid (PGA) and added to the slurry. 
     
     
       14. The process of  claim 11 , wherein preparing the slurry includes the step of reducing particle size of the alkaline solids. 
     
     
       15. The process of  claim 14 , wherein the byproduct polyester stream is added while preparing the slurry. 
     
     
       16. The process of  claim 11 , wherein the slurry includes poly hydroxy organic acids.